She is Flan's grandmother. Despite her apparently greatly caring for him, Flan commented that she made awful bento lunches.
Flan's grandmother appears to be very kind, as she offered to get Mammon milk and dutifully cares for her grandson Flan.
Flan's grandmother has white hair pulled into a bun, and wears a long brown-ish dress. She has wrinkles on her face due to old age.
Flan's grandmother first appears, informing Mammon that Flan was playing upstream. After informing him of this, she goes to get Mammon milk, but is surprised to see that Mammon had disappeared.